mitchell



(No Model.) 2 Sheets-Sheet 1. J. R. MITCHELL &I'. X. FISCHER.

BOILER.

Patented Dec. 19, 1882.

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(No Model.) 2 Sheets-Sheet 2.

J. R. MITCHELL & F. X. FISCHER.

, BOILER. No. 269,308. Patented Dec. 19, 1882.

UNITED STATES JOSEPH R. MITCHELL AND FRANK X. FISCHER, OF SAN FRANCISCO, CAL.

BOILER.

SPECIFICATION forming part of Letters Patent No. 269,308, dated December 19, 1882.

Y Application filed May 22, 1882. (No model.)

To all whom it may concern:

Be it known that we, JosEPH R. MITCHELL and FRANK X. FISCHER, of the city and county of San Francisco, State of California, have invented an lrnproved Boiler; andwe do hereby declare the following to be a full, clear, and exact description thereof..

Our invention relates to certain improve ments in engine-boilers; and it consists in certain details of construction which will be more fully explained by reference to the accompanying drawings, in which Figure l is a longitudinal vertical section. Fig. 2 is a transverse section through the front ofboiler. Fig.3is atransverse section through the middle of boiler. Fig. 4 is a transverse section through thecombustion-chamber. Fig. 5 is a detail of construction.

A is the cylindrical shell of our boiler, which is intended to be mounted upon wheels and be portable. From the sides of the cylinder double walls B extend downward, forming pendulous water-legs, and have a bottom uniting them at such a distance below the boiler as to form an independent chamber, the front portion of which forms a fire-box and ash-pit, with a hollow tubular water-bridge wall or drum, 0, at its rear end, suitably connected with the boiler. by pipes, so as to provide a circulation through it. The flame and products of combustion pass over the bridge-wall and beneath the boiler and into a rear combustionchamber, D, from which theyreturn to the front through tubes E, extending through the boiler, and escape through the chimney F. The bottom is formed in three sections, G H I, the section Gr being bolted beneath the ash-pit, and being removable to give access to it. The second section, H, occupied the middle portion, and is also removable to inspect the circulating-pipes. The rear section, I, is that portion resting upon the bolster, and is notremovable. The wallsB have plates B- bolted to their rear ends and extending toward the rear, forming an incline outward from top to bottom, as shown. The bottom plate, G-, is also extended backward and turned up at the rear, and with these extended sides forms the ash-pit. A plate, J, extends downward from the drum 0 to the floor, to prevent the passage of an aircurrent beneath the drum, and the front end of the floor is stiffened by transverse angleirons K, which are bolted to it. These angleiron braces also serve to form a fire-proofjoint where the bottom sections, G H I, meet by lapping over them, and they retain a sufficient amount of ashes between them to keep the bottom protected from too much heat.

The bolster L extends across beneath the end of the combustion-chamber, and is suitably secured to the bottom plate, and the axle M turns upon the king-bolt N, as shown. A piece of angle-iron, 0, is bolted across the bottom outside, and corresponding with one of the inner angle-irons, to give the bottom extra stiffness and serve as a point for the attachment of brace P for the king-bolt. bolster L project beyond the sides of the water-legs, and both it and the axle Q have braces R, extending up on each side to the cylindrical shell of the boiler, where their upper ends are securely bolted. This is to stiffen the waterlegs and preventthe straining of. the rivet-joint by the side swing or surge of the engine and boiler in passing over uneven ground. Boilers made with pendulous water-legs, as shown in this case, and having no solid fire-front, are very easily loosened at. the rivet-joints if not very firmly braced, and these braces R stren gthon them at this point. At the point where the rearaxlepasses through the plates B they are strengthened and relieved from strain by the plates S, which'are bolted or riveted to the outside of the water legs B and walls B. These plates are notched at T to fit over the axle, and caps or clamps U extend below the axles and are drawn up firmly against them by bolts to, which are tapped into the lower edges of the plates S, these latter being made of considerable thickness for that purpose as well as to give the requisite strength. By this combination of braces and castings the waterlegs are rigidly held in position and thejoints kept tight. The bottom of the ash-pan is inclined upward toward the front, so that the brake-bar X may pass beneath it and stand the same distance from the ground as the rear end of the ash-pan. This is necessary, because the ash-pan is so near the ground that with any other construction the brake-bar would strike. The rear axle is preferably bent or cranked so as to pass above the furnace-door.

The ends of the p The drum 0 extends across the space between the water-legs below the cylindrical shell of the boiler, as shown, and the feed-water pipe V is placed opposite the drum, so as to feed water directly into it, thereby avoiding the risk of crackingthe furnace-sheet,which occurs when the feed-water is pumped directly into the water-legs and impinges against the sheet. The circulation and blow-off pipe W extends forward from the drum, and a vertical pipe, W, extends from the bottom of the boiler-shell down through the bottom of the furnacc',where a blow-off valve is fixed, thus making asimple and effective arrangement for the circulation and blow off. The rivet-joints of the waterlegs B are protected from the heat in the combustion-chamber by liners or plates at, which are riveted over them with an air-space between.

Having thus described our invention, what we claim as new, and desire to secure by Letters Patent, is

1. In a portable boiler having the pendulous water-legs B and wheel-axles, as shown, the inclined braces R, extendingupward from the bolster and rear axle, respectively, and secured to the boiler-shell, substantially as and for the purpose herein described.

2. In a portable boiler having the pendulous water-legs and the closed bottom, as shown, the walls B, having the supplemental plates B, extended back from the vertical plane of the boiler-head, in combination with the floorplate Gr, extended back to the same point and turned up, substantially as and for the purpose herein described.

3. In a portable boiler having pendulous water-legs, and the axle Q, passing through the plates 13 in rear of the furnace, the plates S, notched to tit the axle and bolted to the walls B B", in combination with the caps U andbolts a, substantially as and for the purpose herein described.

4. In a boiler, and in combination with the pendulous water-legs B, the inclined bottom plates, G H I, formed in sections and secured independentlyof each other, substantially as herein described.

5. In a boiler having the pendulous waterlegs B and sectional bottom G H I, the transverse angle-irons K, bolted to the bottom plates, substantially as and for the purpose herein described.

6. In a boiler having the walls B, bottom plates, G H I, and the fixed axle Q, and the axle M, with its bolster N and king-bolt brace P, the exterior angle-iron, O, and the corresponding interior angle-iron, K, bolted to the bottom and having an attachment for the brace, substantially as herein described.

7. The boiler A, with thewater-legs B and the transverse connecting-drum G, in combination with the horizontal pipe W, extending forward beneath the boiler, and the vertical pipe WV, connecting with its front end, and having a cook or valve to discharge or blow off beneath, substantially as herein described.

8. The protecting plates or liners to, extending over the rivet-joints of the water-legs B within the rear eombustion-chamber, substantially as herein described.

In witness whereof we have hereunto set our hands.

JOSEPH R. MITCHELL.

FRANK X. FlSUHER. Witnesses:

E. H. THARP, S. M. THARP. 

